1. Field of the Invention
The present invention relates generally to a fuel supply control system for a multi-cylinder internal combustion engine. More specifically, the invention relates to a fuel supply control system which can adjust a fuel supply amount for respective engine cylinders for suppressing fluctuation of the outputs of respective cylinders, thereby suppressing engine speed fluctuation in each engine revolution cycle, for better engine driveability.
2. Description of the Background Art
The U.S. Pat. No. 4,562,817, issued on Jan. 7, 1986 discloses a so-called multi-point fuel injection internal combustion engine which is designed for injecting a controlled amount of fuel for each individual cylinder at mutually independently controlled timing. Such a multi-point fuel injection-type internal combustion engine generally exhibits good and precise response characteristics for variation of the load since precise fuel injection amount control can be performed with respect to each of individual engine cylinders.
However, on the other hand, such a multipoint fuel injection system for the internal combustion engine has a drawback in causing fluctuation in outputs of respective cylinders when fuel injection characteristics at respective fuel injection valves for respective engine cylinders vary due to secular change, for example. This causes variation of fuel distribution for respective engine cylinders to cause fluctuation of the engine speed during each engine revolution cycle. This clearly degrades engine driveability and engine idling stability and causes surging and so forth.
Furthermore, such output fluctuation among respective individual engine cylinders tends to cause degradation of engine performance and fuel economy. In the worse case, fluctuation of fuel delivery for respective engine cylinders may cause fluctuation of exhaust characteristics in each engine revolution cycle to damage a catalyst converter in an exhaust system.